21-03-2014, 04:57 PM
ACUTE RHEUMATIC FEVER
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Acute rheumatic fever (ARF) is an acute autoimmune disease that occurs as a sequel of group A beta-hemolytic streptococcal infection.
It is characterized by inflammatory lesions of connective tissue and endothelial tissue, primarily affecting the joints and heart.
aPthophysiology and Etiology
Most first attacks of ARF occur 1 to 5 weeks (average 3 weeks) after a streptococcal infection of the throat or of the upper respiratory tract.
Peak incidence occurs in children ages 6 to 15. Incidence after a mild streptococcal pharyngeal infection is 0.3% and after a severe streptococcal infection is 1% to 3%.
Family history of rheumatic fever is usually positive.
Streptococcal infection abates with or without treatment; however, auto-antibodies attack the myocardium, pericardium, and cardiac valves.
Asch offs bodies (fibrin deposits) develop on the valves, possibly leading to permanent valve dysfunction, especially of the mitral and aortic valves.
Severe myocarditis may cause dilation of the heart and CHF.
Inflammation of the large joints causes a painful arthritis that may last 6 to 8 weeks.
Involvement of the nervous system causes chorea (sudden involuntary movements).
Clinical Manifestations
Documented or undocumented group A beta-hemolytic streptococcal infection is usually followed in several weeks by fever, malaise, and anorexia. Major symptoms of ARF may appear several weeks to several months after initial infection.
Major Manifestations
Carditis manifested by systolic or diastolic murmur, prolonged PR and QT intervals on ECG, and possibly by signs of CHF.
Polyarthritis pain and limited movement of two or more joints; joints are swollen, red, warm, and tender.
Chorea purposeless, involuntary, rapid movements commonly associated with muscle weakness, involuntary facial grimaces, speech disturbance, and emotional lability.
Erythema marginatum nonpruritic pink, macular rash mostly of the trunk with pale central areas; migratory.
Subcutaneous nodules firm, painless nodules over the scalp, extensor surface of joints, such as wrists, elbows, knees, and vertebral column.